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TI-2021-10581 Aliases CVE-2021-29964GHSA-6mgf-v5gc-vgc7

Out-of-bounds read in Mozilla Thunderbird

Priority LOW 33CWE-125Published · Updated

Key facts

Attack vector
Local
Privileges required
None
User interaction
Required
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
High · None · High
Fix status
Partial Red Hat: 1 without a fix

Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat.

Summary

A locally-installed hostile program could send `WM_COPYDATA` messages that Firefox would process incorrectly, leading to an out-of-bounds read. *This bug only affects Firefox on Windows. Other operating systems are unaffected.*. This vulnerability affects Thunderbird < 78.11, Firefox < 89, and Firefox ESR < 78.11.

Why it matters now

EPSS 0.00816 57th percentileScored 2026-11-07
Fix Partial Thunderbird (Mozilla): 78.11Firefox (Mozilla): 89+1 more productRed Hat: 1 without a fix

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
MozillaThunderbirdbefore 78.1178.11Patch availableCNA
MozillaFirefoxbefore 8989Patch availableCNA
MozillaFirefox ESRbefore 78.1178.11Patch availableCNA
  • Thunderbird VendorMozilla Affected before 78.11 Fixed in 78.11 Patch available CNA
  • Firefox VendorMozilla Affected before 89 Fixed in 89 Patch available CNA
  • Firefox ESR VendorMozilla Affected before 78.11 Fixed in 78.11 Patch available CNA

CPE configurations NVD · 4

CPEVersionsRoleVendor
cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*before 89.0VulnerableMozilla
cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:*before 78.11VulnerableMozilla
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*before 78.11VulnerableMozilla
cpe:2.3:o:microsoft:windows:-:*:*:*:*:*:*:*not specified by NVDRunning onMicrosoft
  • cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* Versions before 89.0 Vulnerable ·Mozilla
  • cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:* Versions before 78.11 Vulnerable ·Mozilla
  • cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* Versions before 78.11 Vulnerable ·Mozilla
  • cpe:2.3:o:microsoft:windows:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Microsoft

Remediation

  • Fix · CNA Thunderbird (Mozilla) Fixed in 78.11
  • Fix · CNA Firefox (Mozilla) Fixed in 89
  • Fix · CNA Firefox ESR (Mozilla) Fixed in 78.11

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Release ·

    Mozilla Firefox 89

    5 records Highest priority Priority MEDIUM 1 MEDIUM, 4 LOW

    Other records, highest priority first

    • TI-2021-10584 Out-of-bounds write in Mozilla ThunderbirdPriority MEDIUM 41
    • TI-2021-10582 A malicious website that causes an HTTP Authentication dialog to be spawned could trick…Priority LOW 25
    • TI-2021-10579 Firefox for Android would become unstable and hard-to-recover when a website opened too…Priority LOW 21
    Show all 5 records →
  • Release ·

    Mozilla Firefox ESR, Thunderbird 78.11

    2 records Highest priority Priority MEDIUM 1 MEDIUM, 1 LOW

    Other records, highest priority first

    • TI-2021-10584 Out-of-bounds write in Mozilla ThunderbirdPriority MEDIUM 41
    Show all 2 records →

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Enterprise Linux 6AffectedNo fix planned: Out of support scope
Not affected: 2 products
  • Red Hat Enterprise Linux 7
  • Red Hat Enterprise Linux 8

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-29964
  2. 2026-10-03 Alias added: GHSA-6mgf-v5gc-vgc7

References

Advisory 4

  • TI-2024-08981 Use after free in Mozilla Firefox KEVCVSS 3.1CRITICAL 9.8
  • TI-2022-09832 Use after free in Mozilla Firefox KEVCVSS 3.1CRITICAL 9.6
  • TI-2019-08769 Improper input validation in Mozilla Firefox ESR KEVCVSS 3.1CRITICAL 10.0
  • TI-2010-03577 Mozilla Firefox 3.5.x through 3.5.14 and 3.6.x through 3.6.11, Thunderbird 3.1.6 before… KEVCVSS 3.1CRITICAL 9.8
  • TI-2023-04799 Out-of-bounds write in Google Chrome KEVCVSS 3.1HIGH 8.8
  • TI-2023-04477 Out-of-bounds write in Google Chrome KEVCVSS 3.1HIGH 8.8
See all 3444 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences